Circuit interrupter housing



Dec. 8, 1953 s. l. LINDELL ET AL CIRCUIT INTERRUPTER HOUSING 3Sheets-Sheet l Filed March 30, 1951 mi? YU.

INVENTORS. ande@ Dec. 8, 1953 S. l. LINDELL ET AL CIRCUIT INTERRUPTERHOUSING Filed MarCh 30, 1951 3 Sheets-Sheet 2 INVENTORS.

CIRCUIT INTERRUPTER HOUSING Patented Dec. 8, 1953 UNITED STATES PATENTOFFICE CIRCUIT INTERRUPTER HOUSING Sigurd I. Lindell, Chicago, andCharles H. Baker,

Maywood, Ill., assignors to S & C Electric Company, Chicago, 1.1L, acorporation of Delaware Application March 30, 1951, Serial No. 218,448 9Claims. v(Cl. 20.0.1120) Tlhis invention relates, generally, to circuitinit is desired to increase the resistance of the outer terrupters, andit has particular relation to yhoustube formed oi the materials abovenoted to ings for high voltage circuit interrupters. it coninternalpressure, a liner in the form of a vulstitutes an improvement over thecircuit intercanizeel fibre tube or other tough material is lorupterhousings disclosed in application Serial 5 cated within the former andthe solid arc ex- No. 273,538, iileii February 2'?, 1952 and inaptinguishing material, such as boric acid, is posiplication Serial No.filed May 28, 1949, tioned therein.

now Patent No. 2,5S9,i87, granted June 3, 1952, is set forth inapplication Seria-1 No. 273,638, all to the assignee of thisapplication. the granular solid arc extinguishing material is Thetubular Yhousings for circuit inter- 1U compacted into a grooved innersurface of the rupters sl'loivn in these applications are subjectedtubular hous'ng or into such a surface of the to relatively high opencircuit voltages after an libre liner. The purpose of this is toincrease are has been drawn therein and extinguished. the creepage andstriking distance over the outer Where the normal frequency voltageimpressed Surface of the llils of solid arc extinguishing across thetubular housing` is of the order of sevl materia-l at the junctionbetween it and the aderal thousand volts, for example 69 and jacentsurface of the housing and to insure that Where the Hmmm frequencyVoltage may be 9X- the arc will not restrike here. When a liner ofceedefi to a great extent by transient voltages ble or other material ofsuitable physical proparising from various sources, diiculty has beenerbes iS omployd to provide the desired resistencountered particularlyin high current capac- 20 anc@ to internal pressure, diiiiculty has beenenity iuterrupters employing nigh strength liners countered 1n producinga Solid homogeneous within the insulating housing in making certainOuter housing Wall and satisfactory bonding be* that any regnition orrestriking of the are Will til/'GSH it and lille libre llYleCl 130DTSVGD reignitale place only in the bore Where it is originally lOn 01Testflklng 0f the IC alOYle' the junction drawn extinguished a: #l Whereit can be sub- 2 therebetween 01' through longitudinal voids in jectedto the arc extinguishing action of a gas or the tubular hOuSrlg itself.This llas been pof- Water vapor evolving medium such as vboric acidCUlTlY ilue Where the wall thickness of the m. magnesium homie. lammatedtube formed of rolled paper and phen Consel-mgm@ ik@ circuit interrupt@housings nolic condensation product has a thickness above just mentionedthere is employed an outer tube e that is weather has little tendency toinch, for example 1/2 inch to inch, and Where the thickness of the libreliner is about 1/4 inch.

perla-it leakage paths over its external surface, FOY the lf-loSOllSpointed out in application Sebas goed galega-C quali'ies, and is Capableof rial No. 273,633, the nbre liner has a length about withstandingsevere lectric stresses. However, equal t0 half that 0f the tubulin'housing and iS this outer tube mechanically is relatively weak 10C-atedmidway 'between its ends. For certain and unable under all operatingIconditions to Villtaes a tube length 0f Ovol four feet is requiredwithstand the high internal pressures and other with an externallamelle? Gf three lnclla Such mechanical forces that are incident to theoplllll-SS were mafie by Killing Doper impregnated on or" high currentcircuit iuterrupters. The llll illlelOlC eSIl loyer on layer onto a nbrerua erials preferably used for making these outer 40 11H91" undel' pl855111" e @und thm baking il en Oven WMS arg mue@ laminated paper tubesmpreg to cure the resin. For the Wall thickness required nate-rl thphenolic condensation products, ll? W25 found impractical to follow thisprocemela-ruine resins, porcelain, etc. dule- Due to the reslliencycfthe liner uniform In order to furnish the necessary arc extin- Dl'SSuTe@Ould 110i? b2 mamie-ined during the finishing characteristics there isprovided Within such tube a material which is capable of evolving a 1mg@quantity of water Vapor or other are junction with the fibre liner wasunsatisfactory. when subjected to the heat ef Gas o1 air rockets werepresent in a high percentthe Sonie materials which are satisfactory ageOf assemblies which caused the dielectric ici' this purpose are corioacid and magnesium 50 Structure t0 l0@ YlOlUnfOlm and DFOVded a pathberate, these being granular in character, and where breakdown couldoccur under severe over- ,M manufacturing process. As a result there wasa here. er vuieemzed here either in tubular voltage Conditions ratherthan resin-kine through s l Sustaining-@1m or asasraekcfrings. These thebore where the arc could be extinguished i terials are arranger?, toprovide a bere within readily- ThBSe dllfilltles Bocesitated elaborate ii the are is dra-yu and extinguished. Where 55 test procedures inmanufacturing accompanied tendency for the tube to ldelaminate and the`t to the upper end of which one end of a iiexible conductor 40 isconnected. The other end of the flexible conductor 4t is connected by aconducting strap el to the tubular terminal as shown at the top ofFigure 1B. The purese or the flexible conductor 49 and conducting trapil is to provide a metallic conducting path between the eiftensicn 3s ofthe rod-like terminal le and the tubular terminal SS after thecylindrical contact section 33 moves out of engagement with the contactiingers l. The ilexible conductor is trained over a pulley 4E which iscarried by a yoke 43 that is supported by an end ring 44 carried by theupper end of a compression tube 45. The compression tube is slidabiymounted in the upper end of the metallic tube and is urged upwardly by acoil compression spring t for the purpose of retractinr,r the rod-liketerminal it through the bore it? in the filling il of solid arcextinguishing material when the strain wire and the fusible element 23have been melted as a result of the flow therethrough of overload orshort circuit current.

As pointed out hereinbefore, difiiculty has been encountered infabricating the tubular insulating housing le with the fibre liner iiitherein. in imperfect bond at the junction therebetween btained in ahigh percentage of the manusseniblies and there was a tendency for on ofthe layers of impregnated paper rolled under pressure to raalte up thetubular insulating housing Id due to the resiliency of the liner ontowhich the laminated tub-e was .lis a result there were numerousinstances of voltage breakdown in manufacturing tests between the iibreliner i5 and the tubular insulating housing Ill at the junctiontherebetween or along adjacent layers of the impregnated paper nialringup the housing lll.

In accordance with the present invention as illustrated in Figure 2,these diiculties are overcome by fabricating separately the tubularsulating housing i4 of a phenolic condensation product. rEhis maires itpossible to provide the desired wall thicriess by winding the layers ofimpregnated paper onto a rigid steel mandrel which extends throughoutthe entire length of the finished housing Iii. Thereafter it is cured topolymerize the resin and to nx the insulating and other desirablecharacteristics as may be desired. The housing ifi then provided with aninternally annularly or circumferentially grooved surface as indicatedat preferably by cutting a thread therein. For exemple, in theparticular embodiment illustrated where the outside diameter of thehousing I i is two and Liinches the thread is a one and sa inches-8Class l thread.

As illustrated. more clearly in Figure 3 the liner is provided with anexternally annularly or circumferentially grooved surface El which isformed by cutting a like thread on its outer surface. Also prior toassembly of the iibre liner i5 in the housing M the internal threads I5are cut. rihe end sections 5!! and 55 of the threads it? may be cut to aslightly greater pitch diameter for receiving the tubular terminals 2"and 37. Further there is provided an Unthreaded section 5S for receivingthe exhaust ring 2s.

While the nbre liner l5 constructed as shown in Figure 3 can be threadedinto the grooved surface Fili of the housing I4 lwithout applyinganything to the grooved surfaces, it is preferable to apply thereto anadhesive coating. For this purpose the grooved surface 5e has anadhesive coating, as indicated at 5i, applied thereto and likewise anadhesive coating as indicated at 58 is applied to the grooved surface Elof the libre liner l5. This adhesive is formed preferably of watersoluble urea resin which polynie'rlaes without substantial change involume. minediately after the application of the adhesive coatings 5'!and 51.3 to the grooved surfaces and El, the fibre liner it is threadedinto the insulating housing l so as to provide the composite tubularconstruction illustrated in Figure 1B. Thereafter the composite housingis baked to hasten polymerization of the adhesive.

By employing the intertting annularly grocved surfaces 5t and iii thecreepage and striking .distance over the iibre liner I5 is substantiallyincreased. For example, it may be increased as much as 50% to 100% overthe original creepage or striking distance. The adhesive coatings 57 and'iid ll any voids which might otherwise exist along the boundary betweenthe grooved surfaces and bonds the two members into an integraistructure. After being baked tests have shown that the boundary betweenthe grooved surfaces 5o and E! has a dielectric strength equal to air oftwice the linear istance along the boundary off the adjacent materialsbetween their ends. As indicated the threads forming the groovedsurfaces Sil and 5| :Sor the housing Iii and fibre liner i5 are formedby matching threads. These threads can be modified so that they have aninterference iit thus mechanically pr vide for filling the spacesbetween adjacent threads when the nbre liner l ti is threaded intoposition under the required pressure.

In Figure 4 of the drawings there is illustrated, generally at 60, acircuit interrupter of the separable contact type. The circuitinterrupter 6&3 includes an upper line terminal ci and a lower lineterminal t2 in the forro of a housing which is employed for enclosing anoperating mechanism that is indicated, generally, at Between the lineterminals el and e2 there is provided an insulating housing, showngenerally at t4, which comprises a suitable ceramic material such as atubular porcelain insulating housing having therewithin and coextensivetherewith a liner 65 formed of vulcanized fibre or horn fiber. Theporcelain housing t5 is provided with a grooved inner surface 'l whichis formed by cutting a thread therein prior to the curing of the housing65. Likewise the outer surface of the nbre liner t6 is grooved asindicated at E58 by a suitable cutting tool.

Prior to threading the fibre liner into the porcelain housing 65, theformer is enclosed in a sleeve 69 that is formed preferably of syntheticrubber and has sufficient body to fill the spaces between the threads inthe grooved surfaces 67 and t8 when the rlbre liner et is threaded intothe porcelain housing- 65. in order to facilitate the entry of the fibreliner G53 with the synthetic rubber sleeve thereover, the outer surfaceof the latter can be provided with a suitable lubricant such as talc orthe like.

At its lower end the nbre liner et is arranged to receive an extensionfrom the line terminal housing 62 and the saine is provided with threads1I to iiX the same in position. The fibre liner 65 has a bore 12extending therethrough in which the arc is drawn and extinguished andthrough which a rod-like terminal 73 is movable by the operatingmechanism 53.

At its upper end the rod-like terminal 'I3 has Contact lingers 'lllwhich engage a Contact sleeve 'l5 that is threaded at l5 into the upperend of the fibre liner SB. The contact sleeve l5 is threaded intermedateits ends at 11 for threaded engagement with the line terminal Si at theend of the insulating housing te. An insulating trailer i8 is movablewith the rod-like terminal 63 into the bore l2 of the libre liner E5 forthe purpose of confining the are between its outer surface and this borewhen it drawn between the contact lingers 'M and the contact sleeve 1E.

Since certain further changes can be made in the foregoing constructionsand different embodiments o the invention can be niade without departingfrom the spirit and scope thereof, it is intended that all matter shownin the accompanying drawings and described hereinbefore shall beinterpreted as illustrative and not in a limiting sense.

What is claimed as new is:

l. In high 'voltage circuit interruptor, in combination, an tube havinga length several tiines its diameter and having a threaded inner surfaceover a length several times its diu arneter, line terminals at the endsof said tube, a one-piece tubular self-sustaining liner having a lengthseveral times its diameter and having a threaded outer surface threadedinto said tube, the space occupied by liner and said tube coextensivetherewith being free from voids and no path being provided therebetweenalong which current can flow or an are is likely to be struck,stationary conducting ineans extending from each line terminal into saidtube for a substantial distance with the inner end of each conductingmeans projecting into the correspond-- ing end of said liner, and meansinterconnecting said conducting means ior drawing aro within said tubeand liner on operation of the interruptor, the break distance betweenthe terminals of said are drawing means in the circuit open positionbeing less 'than length of the juxtaposed threaded surfaces oi said tubeand liner.

2. In a high voltage circuit interrupter, in coinbination, an insulatingtube having a length several times its diameter and having a threadedinner suri'aee over a length several times its diameter, line terminalsat the ends of said tube, a onepiece tubular -sustaining liner having alength several times its diameter and having a threaded outer surfacethreaded into said tube, the space occupied by said liner and said tubecoextensive therewith free from voids and` no path being providedtherebetween along which current can flow or an are is likely to bestruck., stationary conducting means extending from each line terminalinto tube for a substantial distance with the inner end of eachconducting means projecting into the corresponding end of said liner,said liner having an annularly grooved inner surface, a filling of areextinguishing material compacted into said grooved inner surface andhaving a bore from the surface of which an are extinguishing medium canbe evolved due to the heat of the are, and means interconnecting saidconducting means for drawing an arc within said bore on operation of theinterruptor, the breal: distance between the terminals of said arcdrawing means in the circuit open position being less than the lengthoi' the juxtaposed threaded surfaces oi tube and liner, said conductingmeans acting to distribute voltage stress applied to said line terminalsto prevent arcing therebetween externally of said tube and applying thefill - struck, a st voltage stress to the ends said juxtaposed threadedsurfaces and the ends of the juxtaposed surfaces of said liner saidfilling of eX" tinguishing material whe A by any strucl; betweenconducting means formed and extinguished in said bore.

3. The invention, as set in the insulating is a product and the liner isiorinei o bre.

ll. rlhe invention, as set iori4 claim l, where in the insulating tub isfornire-d of porcelain and the liner is formed o- 5. The invention, asset io in a layer oi insulating polJ eed adhesive niaterial whosevoluine r ns substantially constant alter polymerization interposedbetween the juxtaposed threaded surfaces oi the tube and liner.

6. The invention, as set forth in clainl l, ivhere in a layer of Watersoluble urea resini nterposed between the juxtap sed 'threaded su tubeand liner.

'7. The invention, in a layer oi synth 1c r tween the juxtaposed thitube and liner.

Si. ln a high voltage circ 1' bnation, an insulating tube having alength several tiines its having its inner suriace midway over a lengthegual to hall' thl` in claim l, where olie condensation nds t e lengthoi the tube, line terminals at the ol tube, one-pieee tubularself-sustaining liner equal tube, the space occupied by liner and saidtube eooitensive therevvitl hre from voids and no tl being prov veenalong wh. h current can f o, an are is likely to be 'uct-or extending ^dtube and into `l liner, and means r conductors for drawiroin uneterminal ti e pending end o' ereonnectings nig an are within said l tionoi the intel A tween tl terminals oi saL in the circuit open po,n .ionbeing leW than the length oi" said liner.

ln a high circuit .interrupt-er, in coinbination, an insulat` ig tube hface i.. dway its threaded ov r a length equal to half length of thetube, line terr at the ends said tube, a one .bolar selisustaining linerequal e length no path being provided tl. ereb current can ilo'iv or anare iU be struck, a stationary tubular eonouotor 'ending from each lineterminal into said tube and the corresponding er, an. annularly gros vedextinguir-shi l! ,i along which ze, :.ii

into

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conductors d applysaid juxta- References Cited in the 111e of thispatent UNITED STATES PATENTS Number Name Date 2,073,565 Ruppel Mar. 9,1937 Number 10 Name Date Rawlins et a1 Jan. 19, 1943 Triplett May 18,1943 McMahon July 27, 1943 McMahon Sept. 7, 1943 Rawlins et a1 Sept. 11,1951 Fahnoe Sept. 11, 1951

